Synthetic hydrogels of high purity and stability have been prepared in which the following properties can be controlled and varied over a wide range: fixed positive charge, fixed negative charge, water content, tacticity (stereochemistry), and absorption properties (such as "pore size"). Such gels are useful model systems for studying cell/gel substrate interactions and gel/blood interactions and may be useful as models for the gel-like nature of the cell outer periphery. Preliminary studies of gel interactions with plasma components and blood cells are underway in the present grant. In this application we propose to: 1. Expand and complete the interfacial characterization of gel/water and gel/plasma interfaces with respect to ion interactions, low molecular weight solutes of particular interest (salicylate, fatty acids, etc.) and plasma proteins. 2. Correlate the gel interface properties (zeta potential-charge, interfacial tension, interface structure, surface functional groups) with the protein adsorption behavior. 3. Correlate gel interface properties with platelet and leucocyte adhesion, retention and platelet activation. 4. Select several gels with optimal interface properties for minimal platelet/leucocyte interactions to study as coatings and grafts on conventional polymer substrates. 5. If time permits, consider sustained drug release of bioactive agents through the gel interface to optimize blood compatibility. Such optimized systems should have application in a wide variety of devices for clinical blood-contact applications as well as serving as research tools for hematological studies where minimal interactions with a substrate or container are desired.